The present invention relates to a device for assembling cardboard blanks and blanks of plastic material, particularly for making display packages of the type comprising an opening or window straddling at least one edge or corner of the package and which is closed by a stiff, transparent sheet of plastic material having cut-outs or notches at the ends of its folding lines. Such display packages and their method of making are already described in U.S. Application 329,335, filed Dec. 10, 1981 and the corresponding French Patent Application No. 80 26 305 of Dec. 11, 1980 and its Patent of Addition No. 81 13 025 of July 2, 1981.
The U.S. application (and the French Patent Applications) relate to a method and apparatus where a blank of pre-grooved plastic material is placed onto a pre-cut cardboard blank which has previously been coated by an adhesive material. The application of this technique has proved to be difficult and costly. As a matter of fact, it requires a positioning or alignment which must be extremely accurate for the plastic blank relative to the blank or sheet of cardboard.
The U.S. application also discloses an assembling method according to which the grooving of the blank of plastic material is performed after the sealing or adhering of that blank with the cardboard blank. This grooving can also be carried out at the same time as the sealing of the plastic blank, and preferably, by a high frequency press.